Attack on the uncastled king: queen to d4 (a1·10)
c9-18749naming tag (square·N)Opens in the app if installed, otherwise downloads the APK.
The tactical motive
Chess960 twist: use the unusual starting setup of the pieces.
Uncastled king: the enemy king is stuck in the centre — punish it before it castles.
Winning tactic: there is a move that gains a decisive advantage — find it.
Difficulty 1200 ShuffleRating — club-player level.
White to move — find the best continuation
How to recognize this tactic
In Chess960 the pieces start on unfamiliar squares, so tactics appear earlier and from unusual angles. Do not trust classical patterns — read the actual lines of the bishops, the rooks and the queen from where they really stand in this position.
An uncastled king in the centre is a standing target. Look for ways to open the central files and diagonals against it with checks and threats before it can shelter — every tempo the king spends in the middle is a chance for a combination.
This position hides a concrete tactic that wins material or mates. Start with the most forcing candidate moves — checks, captures and threats — and calculate each to a clear end before choosing; the winning line is usually the one the opponent cannot meet.
General method: before you move, list the forcing candidates — every check, every capture, every direct threat — and calculate those first. The solution to a tactic is almost always among them.
Position on the board
White: king c1, queen a1, rook e1, bishop g2 g3, knight e3, pawn c2 f2 h2 a5.
Black: king c8, queen a8, rook b8 d8, bishop d4 g6, pawn g4 d5 g5 h5 a6 c6.
10 white and 12 black pieces are on the board; the puzzle position arises after move 20.
The position in numbers
Black are ahead by 4 points of material (27 against 31; pawn = 1, knight and bishop = 3, rook = 5, queen = 9) — the tactic has to convert or outweigh that.
The white king stands on c1, the black king on c8.
It is White to move on move 20, with 38 legal replies to weigh — only the line that keeps the advantage solves the puzzle.
White keeps 4 pawns, Black 6. Files fully open (no pawns of either colour): b, e — natural highways for the rooks and queen. Half-open for White: d, g.
The White king has 2 empty squares to step to right now — the fewer they are, the closer a mating net.
Solution & explanation
Main line
20. Qxd4 Qb7 21. Bxb8 Qxb8 22. Bf1 Qf4 23. Bxa6+
Why it works
- Great move! queen to d4 keeps the pressure (+3.8).
- Well found: bishop to b8 (+3.9).
- A natural move: bishop to f1.
- Best move. bishop to a6 is exactly what the engine plays (+3.7).
- You win a piece — the rook.
- If instead Qb7, then Bxb8 and you win the rook.
Move by move
- 20. Qxd4 — queen to d4 (capture)
- Qb7 — queen to b7
- 21. Bxb8 — bishop to b8 (capture)
- Qxb8 — queen to b8 (capture)
- 22. Bf1 — bishop to f1
- Qf4 — queen to f4
- 23. Bxa6+ — bishop to a6 (capture) with check
Types in this puzzle
Overload
One defender guards two things — it cannot do both jobs.
Overloading exploits a defender with two jobs at once — guarding a piece and covering a mating square, for instance. It cannot do both: your first strike forces it to handle one duty and abandon the other. Find the overworked piece by asking what happens to each of its charges if it gets distracted. Then hit one target and collect the other — an overloaded defender only pretends to defend.
Only move
Everything else loses — find the only move that holds.
An only move is a position where everything loses except one single continuation. You cannot play "by hand" here: run through fundamentally different defenses — run away, block, trade, counterattack — and discard the ones that fail. The hallmark of these puzzles is that the obvious moves lose quickly while the solution often looks strange. First understand exactly what the threat is — then the one saving move reveals itself.
Uncastled king
The king lingered in the middle — punish the delay.
Punishing the uncastled king: your opponent delayed castling, and now his king is stuck on its starting square under fire. In Chess960 this is deadlier than in classical chess — the king may start in the center or near the edge, and the familiar defensive setups simply do not apply. The signs: the victim still holds castling rights, and the files toward his king are half-open. Open lines before the king manages to hide.
About this position
These pieces come from starting position #778.
SP-778 · BastionScout — A knight on the a- or h-file, king on c or f — the mirror twin lands here as well.
The king starts on c1, the rooks on b1 and g1, the queen on a1.
The king already stands on c1, so castling long moves only the rook, from b1 to d1.
The bishops stand on e1 and f1; their long diagonals reach a5 and a6 once the d- and e-pawns step aside.
One second-rank pawn starts with no defender at all: h2.
The setup belongs to the BastionScout family; read right to left it becomes position 181.
The engine's main line opens with b4.
Morozov Balance Index: 26 of 100 — class C — noticeable edge. Engine evaluation of the starting position: +34 centipawns for White (depth 45, 400 000 000 nodes).
Explore position #778Provenance
Mined from the project's engine self-play games.
Pack 008 · SP-778
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